As explained in more detail hereinbelow, the control valve of the invention is particularly adapted for use in controlling the pressure within a flexible bladder used in immobilizing the spine of an accident victim. The bladder is adapted to be made rigid and hence support the spine when the pressure therein is reduced below ambient through means of a suction pump and provides a number of special advantages when so used. However, it should be noted that the control valve of the invention is not limited to such a use and, moreover, may be employed in arrangements utilizing either negative or positive pressure.
A number of different control arrangements and like devices have been used in pressure control and, in particular, controlling the suction or vacuum pressure produced by a suction pump or similar device. Examples of such devices are disclosed in U.S. Pat. Nos. 3,039,463 (Dickey, Jr. et al); 2,830,260 (Del Chiocca); 3,595,234 (Jackson) and 3,360,007 (Haidek et al). The Dickey, Jr. et al patent discloses a suction control device wherein a sleeve having a T-slot therein is adjusted to permit outside air into a tube so as to vary the suction force without adjusting the vacuum pump. The Del Chiocca patent discloses a valve assembly wherein air enters through the valve stem of a "T" valve and control of the air flow is effected by screwing the valve in and out. The Jackson patent discloses a vacuum control assembly for a medicosurgical suction tube wherein a band which slides over an opening in the valve so as to adjust the vacuum force in the tube. The Haidek et al patent discloses a gas pressure and vacuum pull control valve providing lateral screw adjustment of the in-line gas pressure. Other patents of possible interest include U.S. Pat. Nos. 1,092,043 (Hammond) and 2,176,139 (Lofgren).